This invention generally relates to composite materials and more particularly to a composite material for flexible-walled containers, tanks, fuel cells, and the like as may be applied to various automotive and/or aircraft applications. While the invention will be specifically described with respect to flexible containers for holding various volatile liquids such as for example automotive and/or aircraft hydrocarbon type fuels, it may as well be applied to other container applications for holding any type substance and these may include corrosive liquids and substances as well as non-volatile and non-corrosive substances.
More specifically, the invention relates to a unique fabric-reinforced composite having polymeric or elastomeric facing plys or layers, which composite is characterized by its ability to being formed into a complex container shape or configuration. A container comprised of the subject composite material, may be used in conjunction with a metal housing, tank, can or other type of rigid enclosure or it may be used independently, the manner of its use being dictated by the particular application. For example, a container of the type alluded to may be found in the art of light aircraft fuel cells wherein it is required that the fuel container conform to the complex volume-space provided within an aircraft wing. Containers of this type are also finding application in the automotive industry wherein the fuel tank container may be buried within the vehicle framework so as to be less vulnerable to damage and/or puncture. In either case, the flexible-container must conform to the volume-space provided in the vehicle whether such space is dictated by the body framework or by a separately mounted enclosure specifically designed for the space and into which the flexible-container is placed.
Conventionally, and in particular with respect to an aircraft type application, fuel containers have been made on rigid male forms wherein the structural components of the container are laid up by hand and subsequently cured to the shape of the form. Because of a need for reinforcement material in the aircraft type fuel container, conventional manufacturing techniques as are used for nonreinforced flexible-walled containers could not be applied inasmuch as the fabric reinforcement does not conform well to a complex shaped female mold using vacuum forming operations. Thus, male forms have been and are the conventional manufacturing technique for such complexly shaped containers and these forms are made of various type composition materials or for example a cardboard material that is sufficiently rigid to support the components of the container structure during lay-up and cure but which may be removed from within the cured container by dissolving the form material in a liquid substance. Upon being dissolved, the form material is washed out of the interior of the cured container through openings that are provided in the walls thereof for filling and/or emptying of the container. This prior art process is described in greater detail in U.S. Pat. No. 2,700,181 to R. F. Wilson.
Thus, the present method of making complexly shaped, fabric-reinforced, flexible-walled containers suffers a marked disadvantage in that it requires multiple and manual operations which must be carried out by skilled personnel. A further disadvantage of the present manufacturing operation is the fact that such male forms are individually hand-made for each and every container and the forms are ultimately destroyed in the process of removing them from within the cured container.
In one aspect of the present invention therefore, it is an object to provide a composite material for a complex-shaped, flexible-container that meets various volatile and/or corrosive substance or liquid holding requirements and which container may be manufactured without resort to hand built male forms and manual lay-up of the container structure.
In a further aspect of the present invention, it is an object to provide a composite material and a method of manufacturing a complexly shaped, flexible-container that eliminates male forms and obviates dissolving and washing out of the form material from within the cured container and associated contamination thereby by residual form material that may not have been completely dissolved and washed out of the interior of the container.